containeradapterdemo.java

《java事件处理指南》一书的代码,好东西

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class ContainerAdapterDemo extends JFrame 
                                     implements ActionListener
{
   private JButton addButton;
   private JTextField jtf;
   private JPanel southPanel, centerPanel;
   private int count;

   public ContainerAdapterDemo()
   {
      count = 0; 

/*  A JButton and a JTextField are added to a JPanel.         */
/*  The JPanel is placed in the South quadrant of the frame.  */

      addButton = new JButton("add");
      addButton.addActionListener(this);

      jtf = new JTextField(20);
      jtf.setEditable(false);

      southPanel = new JPanel();
      southPanel.add(addButton);
      southPanel.add(jtf);

/*  The centerPanel registers a ContainerListener.   */

      centerPanel = new JPanel();
      centerPanel.addContainerListener(new ContainerHandler());

      getContentPane().add(southPanel, BorderLayout.SOUTH);
      getContentPane().add(centerPanel, BorderLayout.CENTER);

      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      setBounds(100, 100, 500, 200);
      setVisible(true);
   }

/*  When the "add" button is pressed, a new JButton is placed       */
/*  on the centerPanel.  This action generates a ContainerEvent     */
/*  which is sent to the componentAdded() method. The revalidate()  */
/*  method is used to update the display when a button is added.    */

   public void actionPerformed(ActionEvent event)
   {
      centerPanel.add(new JButton("Button "+count));
      centerPanel.revalidate();
      ++count;
   }

/*  The ContainerListener is implemented as an inner class that     */
/*  extends the ContainerAdapter class.  Only the componentAdded()  */
/*  is overridden.  This method obtains a reference to the JButton  */
/*  that was added to the centerPanel and updates the JTextField    */
/*  to indicate which button was added.                             */ 

   class ContainerHandler extends ContainerAdapter
   {
      public void componentAdded(ContainerEvent event)
      {
         JButton button = (JButton)event.getChild();
         jtf.setText(button.getText()+" was added");
      }
   }

   public static void main(String args[])
   {
      ContainerAdapterDemo demo = new ContainerAdapterDemo();
   }
}